Method of joining glass plates

ABSTRACT

In order to provide a method of manufacturing a glass panel which, in time of a baking process, restrains an internal stress generated in both of glass plates ( 1, 2 ) to prevent a decline in strength, and restrains inorganic and organic substances remaining within a void (V) defined between the glass plates ( 1, 2 ) to prevent deterioration in quality, a method of manufacturing a glass panel comprises the steps of executing a joining process for joining the pair of glass plates ( 1, 2 ) opposed to each other across the void (V) at peripheries thereof by using a low melting point glass ( 4 ) in a melted condition, executing a baking process for suctioning gas from said void (V) through a suction portion disposed in said glass plates while heating said void (V) defined between the glass plates ( 1, 2 ), and sealing said suction portion to seal said void (V), wherein the gas is suctioned from said void (V) with said low melting point glass ( 4 ) being in a softened condition in which a coefficient of viscosity thereof is 10 10  Pascal seconds (Pa·s) or less when said baking process is executed.

TECHNICAL FIELD

The present invention relates to a method of manufacturing a glass panelcomprising the steps of executing a joining process for joining a pairof glass plates opposed to each other across a void at peripheriesthereof by using a low melting point glass in a melted condition,executing a baking process for drawing and removing the gas from thevoid through a suction portion disposed in the glass plates whileheating the void defined between the glass plates, and then sealing thesuction portion to seal the void.

BACKGROUND ART

Conventionally, in manufacture of such glass panel, paste-like lowmelting point glass is applied to peripheries of both of the glassplates and heated to 480° C. or more as shown in FIG. 6 to melt the lowmelting point glass. Thereafter, the glass is cooled to room temperatureand solidified to execute the joining process for sealing and joiningthe glass plates at the peripheries thereof.

Then, the void defined between the glass plates and the low meltingpoint glass which have been cooled to room temperature are heated againto about 200° C. for drawing and removing the gas from the void toexecute the baking process.

Since the baking process has conventionally been executed at thetemperature around 200° C., there have been disadvantages as follows.

As illustrated in FIG. 7, atmospheric pressure acts on surfaces of theglass plates 1A and 2A when the gas is drawn and removed from the voiddefined between the glass plates. The low melting point glass 4A is in agenerally hardened condition at the temperature around 200° C. as in theconventional method, specifically the temperature around 200° C.established by reheating the glass after the glass is once cooled toroom temperature. As a result, the glass plates 1A and 2A undergo aninternal stress as shown in arrows (solid lines) to bulge and bendtoward the void V, which decreases the strength of the glass plates 1Aand 2A. In an extreme case, the glass plates 1A and 2A bear the internalstress at end portions thereof as shown in arrows (broken lines) to bendoutwardly, which leads to a drawback that the glass plates 1A and 2Aeasily break around the end portions thereof.

The glass plates 1A and 2A are heated to 480° C. or more when thejoining process is executed for joining the glass plates. Thus,inorganic substances including Na are generated from the glass plates 1Aand 2A. Also, organic substances are generated from a binder mixed intothe low melting point glass 4A. These inorganic and organic substancesadhere to inner surfaces of the glass plates 1A and 2A. These substancesare not completely drawn and removed from the void by the baking processexecuted at the temperature around 200° C., and remain adhering to theinner surfaces of the glass plates 1A and 2A. As a result, the qualityof the glass panel could be lowered.

Specifically, when the glass plates 1A and 2A comprise special glasswith a special coating having a heat-absorbing or ultraviolet-absorbingfunction applied to the inner surfaces thereof, the inorganic or organicsubstances may remain in and adhere to flaws in the coating on the innersurfaces thereof. As a result, the flaws of the coating becomenoticeable to cause a significant quality deterioration.

The present invention has been made having regard to the conventionalproblems as described above, and its object is to minimize an internalstress generated in the glass plates, when a baking process is executed,to prevent a decline in strength. Another object of the invention is toprovide a method of manufacturing a glass panel capable of restraininginorganic and organic substances from remaining in a void definedbetween the glass plates to the utmost to prevent deterioration inquality.

DISCLOSURE OF THE INVENTION

The characteristic features of a method of manufacturing a glass panelaccording to the present invention are as follows.

The invention according to claim 1, as illustrated in FIG. 3, provides amethod of manufacturing a glass panel comprising the steps of executinga joining process for joining a pair of glass plates opposed to eachother across a void at peripheries thereof by using a low melting pointglass in a melted condition, executing a baking process for suctioninggas from said void through a suction portion disposed in said glassplates while heating said void defined between the glass plates, andsealing said suction portion to seal said void, characterized in thatthe gas is suctioned from said void with said low melting point glassbeing in a softened condition in which a coefficient of viscositythereof is 10¹⁰ Pascal seconds (Pa·s) or less when said baking processis executed.

With the characteristic feature of the invention according to claim 1,since the gas is drawn and removed from the void with the low meltingpoint glass for joining the glass plates at the peripheries thereofbeing in the softened condition in which the coefficient of viscositythereof is 10¹⁰ Pascal seconds (Pa·s) or less when the baking process isexecuted for drawing and removing the gas from the void while heatingthe void between the glass plates, the low melting point glass in thesoftened condition can be deformed even if atmospheric pressure acts onsurfaces of the glass plates as a result of the gas suction. Thisrestrains an internal stress from being generated in the glass platesand further restrains the glass plates from bending outwardly at endportions thereof, thereby to prevent a decline in strength of the glassplates.

Further, the baking process is executed with the low melting point glassbeing in the softened condition in which the coefficient of viscositythereof is 10¹⁰ Pascal seconds (Pa·s) or less, i.e. the temperature ofthe void between the glass plates being around 350° C. Thus, theinorganic substances including Na or organic substances generated intime of executing the joining process and remaining in the void,especially adsorbed to and remaining in the surfaces of the glass platesfacing the void are almost entirely vaporized. Therefore, the inorganicand organic substances remaining on the surfaces of the glass plates canbe reliably drawn and removed through the baking process.

This can prevent deterioration in quality of the glass panel, and evenif the glass plates comprise special glass with a coating applied toinner surfaces thereof having a heat-absorbing or ultraviolet-absorbingfunction, deterioration in quality can be effectively prevented byrestraining the inorganic and organic substances from adhering to flawsof the inner coating.

The invention according to claim 2, as illustrated in FIGS. 3 and 5, ischaracterized in that said baking process is executed after said joiningprocess is executed and before the coefficient of viscosity of the lowmelting point glass which has been in the melted condition in thejoining process exceeds 10¹⁰ Pascal seconds (Pa·s).

With the characteristic feature of the invention according to claim 2,the baking process is executed after the joining process is completedand before the coefficient of viscosity of the low melting point glasswhich has been in the melted condition in the joining process exceeds10¹⁰ Pascal seconds (Pa·s). Thus, a manufacturing process from thejoining process to the baking process, more specifically heating of thevoid between the glass plates and the low melting point glass, can beeffectively and efficiently carried out, compared with the case wherethe glass is once cooled to room temperature after the joining processis completed and then heated again. Also, there is no need to repeatheating and cooling, which restrains more reliably an internal stressfrom being generated in the glass plates.

The invention according to claim 3, as illustrated in FIGS. 1 to 4, ischaracterized in that said suction portion is a suction bore provided inone glass plate of said glass plates.

The suction portion for decompressing the void may be provided atperipheries of the glass panel where the glass plates are opposed toeach other, for example. However, the glass panel includes the jointportions at the peripheries thereof to join the glass plates by the lowmelting point glass as noted above. It is required to ensure the sealingefficiency of the joint portions in order to maintain the decompressedcondition of the glass panel for a long period. For this reason, it isavoided to form the suction portion in the joint portion in thisarrangement, and instead the suction bore acting as the suction portionis formed in one of the glass plates, which ensures the decompressedcondition of the glass panel.

Also, it is conceivable that an extremely narrow gap is defined betweenthe glass plates. If an attempt is made to form the suction bore inopposed portions of the glass plates in such a case, it becomesdifficult to secure an opening area required for suction. On the otherhand, when the suction bore is formed in one of the glass plates as inthis arrangement, an opening area may be relatively freely determined,thereby to facilitate an operation for forming the suction portion.

The invention according to claim 4, as illustrated in FIG. 3, ischaracterized in that a tubular member is inserted into said bore formedin said one glass plate to protrude outwardly of said one glass plate,and a crystalline low melting point is provided around the protrudingportion of the tubular member for adhering said tubular member to saidglass plate to heat and melt said crystalline low melting point glassand decompress a portion around said crystalline low melting point glassand said tubular member, thereby to suction the gas from said void toexecute the baking process.

When the protruding portion is formed by using the tubular member as inthe invention according to claim 4, a sealing operation of the tubularmember is facilitated after the decompression process is completed. Forexample, to heat and melt a distal end of the protruding portion of thetubular member is advantageous when various heating elements areattached.

Also, according to the present method, it is possible to heat only thedistal end of the protruding portion of the tubular member, thereby torestrain the heat generated with heating from being transmitted to thesurfaces of the glass plates. Thus, when the glass plates areheat-tempered, the decompressing process may be executed withoutdiminishing the effect of the heat-tempering process.

Further, in this arrangement, since the crystalline low melting pointglass is used for adhering the tubular member to the glass plate, thedecompressing process is more reliably executed. In the conventionalart, for example, when the portion around the low melting point glass isdecompressed for the baking process, the low melting point glass isfoamed to possibly hamper air-tightness between the tubular member andthe glass plate or deteriorate adhesive strength. In this regard, thelow melting point glass according to the present invention is thecrystalline low melting point glass in which crystallization is promotedand completed in a high-temperature range. Thus, the low melting pointglass in the melted condition is restrained from being foamed even ifthe portion around the low melting point glass is decompressed for thebaking process. As a result, it is possible to reliably and rigidlyadhere the tubular member to one of the glass plates, thereby to attainexcellent air-tightness.

The invention according to claim 5, as illustrated in FIG. 1, ischaracterized in that numerous spacers for maintaining said void betweensaid pair of glass plates are arranged such that a distance between anoutermost row of the spacers positioned closest to edges of the glassplates and peripheral elements including the low melting point glass maybe smaller than a distance between the outermost row of the spacers andan adjacent, second outermost and other rows of the spacers, thereby toseal said void in a decompressed condition.

With the characteristic feature of the invention according to claim 5,numerous spacers are provided in the void between the pair of glassplates, and the void is sealed in the decompressed condition. Thus, itis possible to provide a glass panel of high quality having an excellentthermal insulation effect due to decompression of the void.

Further, in arranging the numerous spacers in the void between the glassplates, the distance between the outermost row of the spacers positionedclosest to the edges of the glass plates and peripheral elementsincluding the low melting point glass is smaller than the distancebetween the outermost row of the spacers and the adjacent, secondoutermost and other rows of the spacers. With this arrangement, theoutermost row of the spacers positioned closest to the edges of theglass plates reliably maintains the void between the glass plates aroundthe peripheries thereof. Therefore, the glass plates are effectivelyrestrained from deforming to bring the peripheries thereof close to eachother. Thus, reflected images can be restrained from distorting at theperipheries of each glass plate, thereby to eliminate visualawkwardness.

The invention according to claim 6, as illustrated in FIGS. 1 and 3, ischaracterized in that said pair of glass plates are placed such that theperipheries of one glass plate of said pair of glass plates may protrudefrom the peripheries of the other glass plate, and wherein thepaste-like low melting point glass is applied to said protrudingportion.

When the baking process is executed before the low melting point glassreaches 10¹⁰ Pascal seconds or more, the low melting point glass whichhas not yet solidified undergoes a force to move inwardly from theperipheries by atmospheric pressure. In this state, if the low meltingpoint glass is insufficient in quantity, the entire low melting pointglass is drawn inwardly of the void, as a result of which the jointportions may not have a normal configuration or may be perforated.

Thus, the paste-like low melting point glass is applied to theperipheries of one of the glass plates protruding from the peripheriesof the other of the glass plates as defined in claim 6, thereby toprovide a sufficient quantity of the low melting point glass and toeliminate the above-noted disadvantages to obtain excellent jointportions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly cut away perspective view of a vacuum double glazing;

FIG. 2 is a sectional view of a principal portion of the vacuum doubleglazing in a manufacturing process;

FIG. 3 is a sectional view of the vacuum double glazing and a suctionsealing device in the manufacturing process;

FIG. 4 is a sectional view of a principal portion of the vacuum doubleglazing;

FIG. 5 is a graph showing a relationship between temperature and time ina joining process and baking process;

FIG. 6 is a graph showing a relationship between temperature and time ina conventional joining process and baking process; and

FIG. 7 is an explanatory view of a principal portion of the conventionalvacuum double glazing.

BEST MODE FOR CARRYING OUT THE INVENTION

A method of manufacturing a glass panel in an embodiment of to thepresent invention will be described hereinafter with reference to thedrawings.

An example of such a glass panel is a vacuum double glazing. As shown inFIG. 1, the vacuum double glazing P comprises a pair of glass plates 1and 2 and numerous spacers 3 arranged therebetween. Thus, the glassplates 1 and 2 are arranged opposite each other with a void V definedtherebetween. Both of the glass plates 1 and 2 are joined at peripheriesthereof by low melting point glass 4 having a lower melting point andlower gas permeability than the glass plates 1 and 2, with the void Vbetween the glass plates 1 an 2 being sealed in a decompressedcondition.

A suction portion formed in either one of the glass plates or extendingthrough both of the glass plates is used for decompressing the void Vdefined between the glass plates 1 and 2.

Transparent float glass of approximately 2.65 to 3.2 mm thick, forexample, is used for the glass plates 1 and 2. The void V definedbetween the glass plates 1 and 2 is decompressed to 1.33 Pa (1.0×10⁻²Torr) or less.

In order to decompress the void V, as illustrated in FIG. 4, a suctionbore 5 is formed in one of the glass plates 1, which bore includes alarge bore 5 a of approximately 3 mm in diameter and a small bore 5 b ofapproximately 2 mm in diameter, for example. A glass tube 6 acting as atubular member is inserted into the large bore 5 a. The glass tube 6 isrigidly bonded to the glass plate 1 by crystalline low melting pointglass 7 having a lower melting point than the glass tube 6 and glassplate 1.

The suction portion for decompressing the void V may be provided at aperiphery of the glass panel where the glass plates 1 and 2 are opposedto each other, for example. However, the glass panel includes jointportions at the peripheries thereof to join the glass plates by the lowmelting point glass 4 as noted above. A reliable sealing performance isrequired at the joint portions in order to maintain the decompressedcondition of the glass panel for a long period. For this reason, thisembodiment avoids forming the suction portion at a joint portion, andinstead the suction bore 5 acting as the suction portion is formed inone of the glass plates 1 and 2, which ensures the decompressedcondition of the glass panel.

Also, it is conceivable that an extremely narrow gap is defined betweenthe glass plates 1 and 2. If an attempt is made to form the suction bore5 in opposed portions of the glass plates 1 and 2 in such a case, itbecomes difficult to secure an opening area required for suction. On theother hand, when the suction bore 5 is formed in one of the glass plates1 and 2 as in this arrangement, an opening area may be relatively freelydetermined, thereby to facilitate an operation for forming the suctionportion.

After an operation for decompressing the void V is completed, the glasstube 6 is melted and sealed at a distal end thereof and then entirelycovered by a cap 8.

The spacers 3 preferably have a cylindrical configuration. They are madeof a material having a compressive strength of at least 4.9×108 Pa(5×10³ kgf/cm²), e.g. stainless steel (SUS304), Inconel 718 or the like,to be endurable against the atmospheric pressure acting on both of theglass plates 1 and 2.

In the case of the cylindrical configuration, the spacers 3 are about0.3 to 1.0 mm in diameter and about 0.15 to 1.0 mm in height.

The intervals between the spacers 3 are set to about 20 mm where theglass plates 1 and 2 are 3 mm thick, for example. This value may bevaried as appropriate with the thickness of the glass plates.

However, in arranging the numerous spacers 3 as illustrated in FIG. 1, adistance L1 between an outermost row of spacers positioned closest tothe edges of the glass plates 1 and 2 and peripheral elements consistingof the low melting point glass 4 is set to be smaller than a distance L0between the outermost row of spacers and an adjacent, second outermostand next rows of spacers. For example, where the distance L0 is set toapproximately 20 mm, the distance L1 is set to 0 to less than 20 mm,preferably about 0 to 15 mm. This is done for the following reason.

The low melting point glass 4 is softened in time of a baking process.On the other hand, the height of the spacers 3 disposed between theglass plates 1 and 2 hardly changes. As a result, when the glass plates1 and 2 are pressed by atmospheric pressure in time of the bakingprocess, the peripheries of the glass plates supported by the lowmelting point glass 4 are easily displaced. To diminish suchdisplacement, portions around the peripheries of the glass plates 1 and2, i.e. portions protruding from positions supported by the outermostspacers 3 should be shortened. Thus, the distance L1 is set smaller thanthe distance L0 in this arrangement. As a result, the peripheries ofboth of the glass plates are effectively restrained from displacing asthe baking process is executed, and reflected images on the peripheriesof each glass plate are restrained from distorting, thereby to eliminatevisual awkwardness.

Next, a process for manufacturing the vacuum double glazing P will bedescribed. It should be noted that this manufacturing process is recitedby way of example and parts of the manufacturing process may beperformed in a reversed order in an actual situation.

First, one of the glass plates 2 not having the suction bore 5 formedtherein is supported in a substantially horizontal position. Thepaste-like low melting point glass 4 is applied to a top surface of theglass plate at the peripheries thereof, and the numerous spacers 3 arearranged at predetermined intervals. Then, the other glass plate 1 isplaced over the spacers.

In this arrangement, as illustrated in FIGS. 1 and 3, the lower glassplate 2 has a slightly larger area such that the peripheries of thelower glass plate may protrude from the peripheries of the upper glassplate 1. This is convenient for application of the low melting pointglass 4.

More particularly, when the baking process is performed before the lowmelting point glass reaches 10¹⁰ Pascal or more, the low melting pointglass which has not yet been hardened undergoes a force to move inwardlyfrom the peripheries by atmospheric pressure. If the low melting pointglass is insufficient in quantity at that time, the entire low meltingpoint glass will be drawn inwardly. As a result, the joint portions maynot have a normal configuration or may be perforated. In view of this, apaste-like material containing a sufficient quantity of low meltingpoint glass 4 is applied to stepped portions formed at the peripheriesof the two glass plates 1 and 2 as noted above, thereby to avoid theabove disadvantages.

Subsequently, as shown in FIG. 2, the glass tube 6 is inserted into thesuction bore 5 formed in the upper glass plate 1. The glass tube 6 isinsertable only into the large bore 5 a of the suction bore 5 and has agreater length greater than the large bore 5 a. Thus, the glass tube 6has an upper portion protruding upward from the glass plate 1. Aroundthe protruding portion of the glass tube 6 is applied the doughnut-likecrystalline low melting point glass 7 for adhering the glass tube 6 tothe glass plate 1. Further, a suction sealing device 9 is placed fromabove as shown in FIG. 3.

The suction sealing device 9 includes a bottomed cylindrical suction cup10 and an electric heater 11 provided within the suction cup 10. Thedevice further includes a flexible suction pipe 12 communicating with aninterior space of the suction cup 10, and an O-ring 13 for sealing thetop surface of the glass plate 1.

Both of the glass plates 1 and 2, covered with the suction sealingdevice 9, are placed substantially horizontally in a heating furnace 14.The low melting point glass 4 is melted by baking to join theperipheries of the glass plates 1 and 2 to seal the void V to complete ajoining process.

More particularly, as shown in FIG. 5, the temperature in the heatingfurnace 14 is raised to 480° C. or above to melt the low melting pointglass 4. Since the melted low melting point glass 4 has excellentwettability for the glass plates 1 and 2, surfaces 4 a facing the void Vbulge into the void V in a sectional view substantially perpendicular tothe glass plates 1 and 2. The crystalline low melting point glass 7around the glass tube 6 is also melted along with melting of the lowmelting point glass 4 to flow into a gap between the large bore 5 a andthe glass tube 6.

The inner temperature of the heating furnace 14 is set to 350° C. orabove thereafter. In this state, the low melting point glass 4 is in asoftened condition with a coefficient of viscosity at 10¹¹ poise, or10¹⁰ Pascal seconds (Pa·s) or less. In other words, the baking processis executed such that, while the low melting point glass 4 is maintainedin a condition in which the coefficient of viscosity thereof does notexceed 10¹⁰ Pascal seconds after the temperature of the low meltingpoint glass 4 is lowered, the void V between the glass plates 1 and 2 isheated, and gas is drawn and removed from the void V through the glasstube 6 inserted into the suction bore 5.

If the inner temperature of the heating furnace 14 is lower than 350°C., the coefficient of viscosity of the low melting point glass 4 willexceed 10¹⁰ Pascal seconds. In such a case, the configuration of thejoint portions is quite stabilized because the problems of failing toobtain a normal configuration of the joint portions or forming throughholes in the joint portions are eliminated. However, it requires a longtime to execute the baking process, which results in a disadvantage ofreducing productivity. Also, the effect of drawing and removing residuesadhering to the glass surfaces facing the void V is decreased. Under thecircumstances, it is preferable to execute the baking process within therange of the coefficient of viscosity being less than 10⁸ Pascal secondsof the low melting point glass 4. In this state, the temperature of thelow melting point glass 4 becomes generally 380° C. or higher.

With respect to the decompressing operation, the interior of the suctioncup 10 is decompressed by using a rotary pump or a turbo molecular pumpconnected to the flexible pipe 12 thereby to decompress the interior ofthe void V to 1.33 Pa or less through the glass tube 6 and the smallbore 5 b.

The void V defined between the glass plates 1 and 2 has been heated to350° C. or above when the baking process is performed. Thus, inorganicsubstances including Na generated from the glass plates 1 and 2 in timeof the joining process and remaining within the void V, and organicsubstances generated from the low melting point glass 4 and remaining inthe void V have been vaporized. Therefore, the inorganic substancesincluding Na and the organic substances are reliably drawn and removedfrom the void V through the flexible pipe 12.

Since the low melting point glass 4 is in the softened condition withits coefficient of viscosity at 10¹⁰ Pascal seconds or less, thesurfaces 4 a thereof facing to the void V bulge and bend toward the voidV as a result of the decompression of the void V, as illustrated in FIG.3.

At this time, the low melting point glass 7 provided around the glasstube 6 is also in a melted condition, but is different from the lowmelting point glass 4 provided around the glass plates 1 and 2. Moreparticularly, the low melting point glass 7 is crystalline, in whichcrystallization is promoted and completed in a high temperature range.Therefore, the low melting point glass 4 provided around the glassplates 1 and 2 is not crystallized but is in the softened condition whenthe baking process is performed, and thus is easily deformed bydecompression and suction of the void V. On the other hand, the lowmelting point glass 7 provided around the glass tube 6 has already beencrystallized and thus is not foamed by decompression within the suctioncup 10. Thus, the glass tube 6 is reliably sealed and bonded to theglass plate 1 by using the crystalline low melting point glass 7.

Subsequently, the distal end of the glass tube 6 is locally heated toapproximately 1000° C. and melted by the electric heater 11. Asillustrated in FIG. 4, the vacuum double glazing P is manufactured bysealing an opening at the distal end of the glass tube 6 and adheringthe cap 8 to the glass plate 1 after a cooling operation. In the vacuumdouble glazing P manufactured in such a manner, the surfaces 4 a of thelow melting point glass 4 facing the void bulge and bend toward the voidV in the sectional view substantially perpendicular to the glass plates1 and 2.

[Other Embodiments]

(1) In the foregoing embodiment, the low melting point glass 4 is heatedto 480° C. or above to execute the joining process, and then the bakingprocess is executed before the coefficient of viscosity of the lowmelting point glass 4 exceeds 10¹⁰ Pascal seconds with a temperaturefall thereof. Instead, the low melting point glass 4 may be cooled toroom temperature once after the joining process is executed, and thenheated again until the coefficient of viscosity thereof reaches 10¹⁰Pascal seconds or less to execute the baking process.

(2) In the foregoing embodiment, the vacuum double glazing P is shown asone example of glass panels. Instead, the present invention may beapplied to manufacture of a plasma display panel or the like in whichthe void V defined between the glass plates 1 and 2 is filled with gas.In such a case, the void V is filled with a predetermined gas after thebaking process is executed.

The glass plates 1 and 2 constituting the glass panel P are not limitedto float glass as described in the foregoing embodiment, but a materialmay be selected as appropriate for various use and purposes of the glasspanel P. For example, it is possible to use, alone or in combination,figured glass, obscured glass having a light diffusing function obtainedby a surface treatment, net glass, wire glass, tempered glass,double-reinforced glass, low-reflecting glass, high-penetrable sheetglass, ceramic print glass, or special glass having a heat-absorbing orultraviolet-absorbing function.

Further, with regard to glass composition, soda silica glass, soda limeglass, boric silica glass, aluminosilicate glass, and various types ofcrystallized glass may be used. The thickness of the glass plates 1 and2 may also be selected as appropriate.

The material for the spacers 3 is not limited to stainless steel orInconel. Instead, it is possible to use metals including iron, copper,aluminum, tungsten, nickel, chromium and titanium, alloys such as carbonsteel, chromium steel, nickel steel, nickel-chromium steel, manganesesteel, chrome-manganese steel, chrome-molybdenum steel, silicon steel,brass, solder and duralumin, and ceramics or glass, which are not easilydeformed by external forces. Each spacer is not limited to thecylindrical shape, but may be of various kinds of shape such asprismatic shape or spherical shape.

INDUSTRIAL UTILITY

The glass panel according to the present invention may be applied tomanufacture of a plasma display panel in which the void V definedbetween the glass plates 1 and 2 is filled with gas, besides the vacuumdouble glazing P as described in the first embodiment.

Also, the glass panel may be used in various fields, e.g. forwindowpanes of buildings and vehicles (automobiles, railway carriages,and ships and vessels), and elements of devices such as plasma displays,and doors and walls of various devices such as refrigerators andheat-retaining devices.

1. A method of manufacturing a glass panel comprising the steps ofexecuting a joining process for joining a pair of glass plates opposedto each other across a void at peripheries of said pair of glass platesthereof by using a low melting point glass in a melted condition,executing a baking process for suctioning gas from said void through asuction portion disposed in said glass plates while heating said voiddefined between the glass plates, and sealing said suction portion toseal said void, wherein the gas is suctioned from said void with saidlow melting point glass being in a softened condition in which acoefficient of viscosity thereof is 10¹⁰ Pascal seconds (Pa·s) or lesswhen said baking process is executed.
 2. A method of manufacturing aglass panel as in claim 1, wherein said baking process is executed aftersaid joining process is executed and before the coefficient of viscosityof the low melting point glass which has been in the melted condition inthe joining process reaches 10¹⁰ Pascal seconds (Pa·s) or more.
 3. Amethod of manufacturing a glass panel as in claim 1, wherein saidsuction portion is a suction bore provided in one glass plate of saidglass plates.
 4. A method of manufacturing a glass panel as in claim 3,wherein a tubular member is inserted into said bore formed in said oneglass plate to protrude outwardly of said one glass plate, and acrystalline low melting point glass is provided around the protrudingportion of the tubular member for adhering said tubular member to saidglass plate, heating and melting said crystalline low melting pointglass and decompress a portion around said crystalline low melting pointglass and said tubular member, thereby to suction the gas from said voidto execute the baking process.
 5. A method of manufacturing a glasspanel as in claim 1, wherein numerous spacers for maintaining said voidbetween said pair of glass plates are arranged such that a distancebetween an outermost row of the spacers positioned closest to edges ofthe glass plates and peripheral elements including the low melting pointglass may be smaller than a distance between the outermost row of thespacers and an adjacent, second outermost and other rows of the spacers,thereby to seal said void in a decompressed condition.
 6. A method ofmanufacturing a glass panel as in claim 1, wherein said pair of glassplates are placed such that the peripheries of one glass plate of saidpair of glass plates may protrude from the peripheries of the otherglass plate, and wherein the paste-like low melting point glass isapplied to the said protruding portion.